/Engine/Source/Runtime/Experimental/Chaos/Public/Chaos/ClusterUnionManager.h
Changes the ChildToParent of a number of particles in a cluster union. bLock will prevent other functions from overriding the ChildToParent (aside from another call to UpdateClusterUnionParticlesChildToParent).
void UpdateClusterUnionParticlesChildToParent ( [FClusterUnionIndex](API\Runtime\Chaos\Chaos\FClusterUnionIndex) Index, const [TArray](API\Runtime\Core\Containers\TArray)< [FPBDRigidParticleHandle](API\Runtime\Chaos\Chaos\FPBDRigidParticleHandle) * > & Particles, const [TArray](API\Runtime\Core\Containers\TArray)< FTransform > & ChildToParent, bool bLock )